JPH0511370B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an insulated wire with excellent heat aging resistance. [Prior art] S-B-S, a type of styrene elastomer
Insulated wires are made by coating the outer periphery of the conductor with a composition mainly composed of block copolymer (S is polystyrene, B is polyisoprene or polybutadiene with hydrogen added to crush the unsaturated parts), unlike conventional plastic coatings. It is attracting attention because it has excellent processability like an insulated wire, exhibits the properties of a rubber-coated insulated wire without crosslinking, and has excellent electrical insulation and toughness. Conventional such compositions generally contain a large amount of mineral oil-free process oil as a softener in order to provide extrudability and flexibility, and the process oil deteriorates due to oxidation at high temperatures. This leads to oxidative deterioration of the polymer as well. Therefore, insulated wires using such compositions as insulators have insufficient heat aging resistance and cannot be used in applications requiring heat resistance. [Problems to be Solved by the Invention] The present invention has been made based on the above, and an object of the present invention is to provide a styrene-based elastomer-coated insulated wire with improved heat aging resistance. [Means for Solving the Problems] The insulated wire of the present invention is made of (a) S-B-S block polymer (S is polystyrene, B is polyisoprene or polybutadiene with hydrogen added to it to destroy unsaturated parts) polymer), (b) polypropylene, and (c) ethylene/α-olefin cooligomer, the weight ratio of component (a)/component (b) is 30/70 to 70/30, and (a)
30 parts of component (c) per 100 parts by weight of component and (b)
It is characterized in that an insulator made of a resin composition containing at least part by weight is provided around the outer periphery of the conductor. In the present invention, S in the S-B-S block polymer of component (a) is a polystyrene block, and B is a polymer block obtained by adding hydrogen to polyisoprene or polybutadiene to destroy unsaturated parts. When hydrogen is added to polyisoprene, B becomes an ethylene-butene-1 copolymer or its analogue, and when hydrogen is added to polybutadiene, B becomes
is an ethylene-propylene copolymer or its analog. The average molecular weight of S is 1000 to 200000, preferably 50000 to 120000, and the average molecular weight of B is 5000 to 200000.
500,000 preferably 10,000 to 300,000. The content ratio (weight%) of S/B is 5/95 to 55/
45, preferably 10/90 to 30/70. (b) Component polypropylene is the above S-B-S
This is necessary for imparting extrusion processability and heat deformation resistance to the block copolymer. The ethylene/α-olefin cooligomer which is the component (c) has the general formula: [(CH ₂ −CH ₂ ) _X (CH ₂ −R CH) _Y ] _Z (R: CnHzn+1, x, y, z: integer ), and the optimal molecular weight is 1000 to 2000. It has been found that by using such a hydrocarbon synthetic oil, the heat aging resistance of a styrenic elastomer composition can be improved. The blending amount of components (a) to (c) must be in the range of 30/70 parts by weight to 70/30 parts by weight (a)/(b), and if the amount of component (b) is too large, The inherent flexibility of component (a) will be impaired, and if it is too small, extrusion processability and heat deformation resistance will decrease. Component (c) must be blended at least 30 parts by weight per 100 parts by weight of the total amount of components (a) and (b); if it is less than this, sufficient extrudability and flexibility cannot be obtained. . In the present invention, in addition to the above-mentioned components, fillers, lubricants, antioxidants, metal damage and deterioration inhibitors, colorants, flame retardants, flame retardant aids, etc. may be added as necessary. Examples of fillers include carbon black, calcium carbonate, magnesium silicate, aluminum silicon, and the like. Flame retardants include metal hydroxides such as aluminum hydroxide and magnesium hydroxide, perchlorocyclopentadecane, decabromodiphenyl ether,
Examples include halogen compounds such as ethylene bistetrabromphthalimide, chlorinated paraffin, and chlorinated polyethylene. Examples of flame retardant aids include antimony compounds represented by antimony trioxide, boric acid compounds represented by zinc borate, and zirconium compounds represented by zirconium oxide. [Example] The formulations shown in each example in Table 1 were kneaded in a Banbury kneader, and then introduced into an extruder to obtain a cross-sectional area of 2
An insulated wire was prepared by extruding the outer periphery of a mm ² copper wire to a thickness of 1.2 mm. The evaluation results of the insulated wires prepared based on the formulations of each example are shown in the lower column of Table 1. For heat aging resistance, a 1mm thick sheet with the same composition was tested.
After heat aging at 158℃ for 7 days, a tensile test was performed at a speed of 500mm/min, and the residual tensile strength was 70% or more.
A test with a residual elongation rate of 65% or more was considered a pass. Flexibility was evaluated as good if the wire was bent 180 degrees and the part did not become cloudy. Extrusion processability was judged from the roughness of the surface of the obtained electric wire. Heat deformation resistance was evaluated by the amount of change in thickness when a 2 mm thick sheet of the same composition was created, placed in a heat deformation tester at 121℃, and a load of 2 kg was placed on it.
% or less was considered to be a pass.

[Table] As is clear from Table 1, Examples 1 to 3 within the scope of the present invention are excellent in various properties including heat aging resistance. Comparative Example 1 uses a conventional paraffin-based process oil and has poor heat aging resistance. In Comparative Examples 2 and 3, the blending ratio of S-B-S block copolymer and polypropylene was outside the specified value of the present invention, and each was inferior in flexibility, extrusion processability, and heat deformation resistance. Comparative Example 4 is one in which the amount of ethylene/α-olefin cooligomer is outside the specified value of the present invention.
Poor flexibility. [Effects of the Invention] As explained above, the present invention provides an insulated wire using a resin composition containing an S-B-S block copolymer, polypropylene, and an ethylene/α-olefin co-oligomer as an insulator. , it is possible to realize an insulated wire with excellent heat aging resistance, flexibility, extrusion processability, and heat deformation resistance.

Claims (1)

[Claims] 1 (a) S-B-S block polymer (S is polystyrene, B is a polymer obtained by adding hydrogen to polyisoprene or polybutadiene to crush unsaturated parts),
Contains (b) polypropylene, (c) ethylene/α-olefin cooligomer, and the weight ratio of component (a)/component (b) is
30/70 to 70/30, total amount of component (a) and component (b)
An insulated wire characterized in that an insulator made of a resin composition containing 30 parts by weight or more of component (c) per 100 parts by weight is provided on the outer periphery of the conductor.